The objective of this project is to continue work, now in progress, in regard to developing non-invasive techniques for detection of coronary thrombosis in vivo and the quantitative evaluation of acute myocardial ischemia. The experimental model consists of intact dogs and utilizes techniques capable of inducing thrombotic and non-thrombotic coronary occlusion. Radioactive tracers as well as radioactively tagged components of the clotting and fibrinolytic mechanism will be used to localize thrombotic and ischemic areas of the myocardium by means of an Anger Camera and body surface scintillation.